1. Field of the Invention
The present invention relates to a vacuum pump including a gas inlet and a quick-rotatable rotor connectable with a flange of a multi-chamber vacuum installation, with the flange having a plurality of suction openings separated by a separation wall(s).
2. Description of the Prior Art
In a number of applications, several vacuum chambers arranged in a row and are connected with each other by bores having a small transmissive capacity. The gas pressure in the vacuum chambers is reduced from one end of the row of the vacuum chambers to another end. The bores are so formed that a particle beam can pass therethrough and, thus, through the row of vacuum chambers. The vacuum chambers with a low pressure often contain an analyzer, e.g., a mass spectrometer.
The state-of-the art discloses different ways of producing vacuum in vacuum chambers and maintain it there.
A first conventional way of producing and maintaining vacuum in a plurality of vacuum chambers consists in providing each vacuum chamber with its own flange. A vacuum pump, which is suitable for the pressure region, is then secured to the flange. This way is no acceptable because of high costs of a plurality of pumps. In addition, there is a need in compact apparatuses. This cannot be realized with a plurality of vacuum pumps.
A second conventional way is disclosed in German Publication DE-OS 43 31 589. This publication discloses a turbomolecular pump having a plurality of suction connections connectable with a respective plurality of vacuum chambers. The suction connections guide the gas to different, axially spaced parts of the rotor. Along the rotor axis there are arranged so-called rotor-stator packages that compress the gas. A high vacuum-side rotor-stator package produces a pressure ratio between its inlet and outlet. The inlet is connected with a first vacuum chamber. The outlet is connected with an inlet of the following rotor-stator package. In addition, the region between the outlet of the first rotor stator package and the inlet of the following rotor-stator package is connected with a second vacuum chamber. Because of the pressure ratio, which is produced by the first rotor-stator package and a poor transmissive capacity between the two, first and second, vacuum chambers the pressures in the two chambers are different. With a corresponding number of rotor-stator packages, several vacuum chambers can be evacuated at different pressures, with a rotor-stator package being associated with each suction connection. However, because the rotors operate with a rotational speed in the range of about ten thousand revolutions per minute, it is difficult to handle very long, in comparison with their diameter, rotors.
Accordingly, an object of the present invention is to provide a vacuum pump for a multi-chamber vacuum installation and having a simplified construction while capable, at the same time, to maintain a pressure difference between at least two chambers.